Mouse anti-Human PJA2 monoclonal antibody, clone 2H22

Energy sensing by the AMP-activated protein kinase (AMPK) is of fundamental importance in cell biology. In the pancreatic beta-cell, AMPK is a central regulator of insulin secretion. The capacity of the beta-cell to increase insulin output is a critical compensatory mechanism in prediabetes, yet its molecular underpinnings are unclear. Here we delineate a complex consisting of the AMPK-related kinase SIK2, the CDK5 activator CDK5R1 (also known as p35) and the E3 ligase PJA2 essential for beta-cell functional compensation. Following glucose stimulation, SIK2 phosphorylates p35 at Ser 91, to trigger its ubiquitylation by PJA2 and promote insulin secretion. Furthermore, SIK2 accumulates in beta-cells in models of metabolic syndrome to permit compensatory secretion; in contrast, beta-cell knockout of SIK2 leads to accumulation of p35 and impaired secretion. This work demonstrates that the SIK2-p35-PJA2 complex is essential for glucose homeostasis and provides a link between p35-CDK5 and the AMPK family in excitable cells.

BackgroundInvasive micropapillary carcinoma (IMPC) of the breast is characterized by its unique morphology and frequent nodal metastasis. However, the mechanism for development of this unique subtype has not been clearly elucidated. The aim of this study was to obtain a better understanding of IMPC.MethodsUsing representative cases of mixed IMPC, mRNA expression in the micropapillary area and usual invasive area was compared. Then, immunohistochemical analyses for 294 cases (76 invasive carcinomas with a micropapillary feature [ICMF] and 218 invasive carcinomas without a micropapillary feature [ICNMF]) were conducted. Clinicopathological analyses were also studied.ResultsDNA microarray analyses for mixed IMPC showed that BC-1514 (C21orf118) was commonly upregulated in the micropapillary area. CAMK2N1, CD1d, PJA2, RPL5, SAMD13, TCF4, and TXNIP were commonly downregulated in the micropapillary area. Immunohistochemically, we confirmed that BC-1514 was more upregulated in ICMF than in ICNMF. CD1d and PJA2 were more downregulated in ICMF than ICNMF. All patients with cases of PJA2 overexpression survived without cancer recurrence during the follow-up period, although the differences for disease-free (p=0.153) or overall survival (p=0.272) were not significant.ConclusionsThe CD1d- and PJA2-related tumour microenvironment might be crucial for IMPC. Further study of the immune microenvironment and micropapillary features is warranted.